Apparatus for controlling highway crossing signals



May 19, 1959 o. c. BETTISON ETAL 2,887,571

APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS Fi-led June 18, 1954 TR. J

5 PSR v 7T i 36 THR.

33 LTER.

BPSR.

3. TER. I

g, l I l 1 INVZENTOR DamdCBethson a ThomasWHags ATTORNEYS way crossing.

sheet of drawings, it will be APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS This invention relates to railroad signaling systems and more particularly to systems which are employed at points of a train in track sections 7T or T the TR relay is energized and its contacts occupy the position shown in the where highways intersect railroad lines, to provide visual I and/ or audible warning signals for warning highway traffic of the presence of an approaching train.

It is an object of this invention to provide a signaling system which encompasses not only the main line tracks but also side tracks which are intersected at a common point by a highway.

It is a further object of this invention to provide for automatic termination of the signal display in the event that a train proceeding toward the cross stops for a predetermined period of time, and to also automatically reinstate the signal display should the stopped train again start up in a direction approaching the crossing. It is a further object of this invention, to provide circuits for providing a safe warning time regardless of the scription andattached drawings in which Figure 1 shows a preferred embodiment of the invention applied to the side tracks on either side of the main line tracks at a high- Turning now to the single noted that the side tracks are divided into a plurality of insulated sections 6T to 11T inclusive. Sections 6T, 8T, 9T and 11T are each further broken up by insulated joints, each of which is by-passed by one of a series of resistors, 13 to 16 and 20 to 23 inclusive.- In addition, the ends of each of these track sections most remote from the crossing are connected by resistors 12, 17, 19 and 24.

For convenience in describing these circuits, the following table defines the relay designations used herein: I

TR-=Track relay BPR=Biased relay repeater BPSR=Biased polar stick relay XR=Crossing protection control relay TPR'= R'epeater relay of a track relay; MR =Master relay LR=Timedelay relay DR-:Com'ponent relay of time delay network TPPR=Repeater of a repeater of a track relay EXR=Control relay for eastbound crossing protection EoRElectric light flasher control relay TER '-Time element relay THR=Thermal relay .WSR=Westbound stick relay ESR=Eastbound stick relay The above designations are conventional and standard in the railroad signalling art.

1.: All of the track sections including the resistors are con- .nected in a series circuit with a battery 25, the primary 27- of a transformer, and a track relay TR. In the absence 3;

drawing.

The secondary winding 28 of the transformer is connectedto a relay BR. This relay is of a type known as a biased polar relay which is responsive to current flow in one direction only. As connected in this circuit, it will operate only onan increase of current in the above mentioned series circuit to open its contact 37, and its operation is momentary. As soon as the transient current dies out, it will reclose its contact. Whenever, therefore, a train moving in track sections 6T, 8T, 9T or 11T in a direction toward the crossing shunts any of resistors 12-24 inclusive, the BR relay momentarily opens its contact 37.

The crossing signals proper are illustrated as a series of lights 46, 47, 48 and 49. These lights are caused to flash on and oif in a continuous manner whenever relay EOR is connected to a source of power such as battery 29. The latter battery also furnishes power for the operation of all the remaining relays except relay BPR which derives its energy from the track battery 25;

The operation of this circuit can be understood by following the operation of its individual components as a train enters, e.g. track section ST and proceeds toward the crossing.

Immediately upon shunting resistor 17 at the far end of this track section, current increases in the series circuit, which comprises all the track sections, the TR relay, the primary 27 of the transformer and battery 25. This increase of current in the transformer winding 27, induces a voltage in the secondary winding 28 which is of such polarity as to momentarily energize relay BR causing it to open its contact 37. Opening of contact 37 disconnects relay BPR from its source of energy, track battery 25, so that it drops its normally closed contacts 35 and 36. Since check contact 38 of the time element relay TER is closed only when TER is de-energized and its timer in the normal position, relay BPR will become reenergized as soon as BR drops out, which as described above, is only a very short interval of time. The momentary opening of contact 36 of BPR however, functions to disconnect relay BPSR from its source of energy, battery 29, and this relay, once deenergized cannot again pick up until its own front contact 30 is by-passed by the closing of contact 39 of relay TER. Before proceeding with a description of relay TER, it should be noted that when relay BPSR dropped, it opened its contact 31, breaking the connection between relay XR and battery 29. Dropping of relay XR closes its contacts 40 and 41 which energizes relay E'OR and connects the lights 46, 47, 48, and 49 to battery 29 through the flasher relay EOR. The signal display will persist until relay BPSR again picks up closing contact 31 and re-energizing relay XR to open contacts -40-an'd 41. l

The function of time element relay TER is tostop the signal warning display after a predetermined time; This timing out of the warning signals is desirable in the event that a train having entered one of sections 6T, 8T, 9T, or -11T, in a direction toward the crossing, stops for an appreciable time.

The dropping of BPSR which is a stick relay, opens one of the contacts 30 and closes the other, which connects relay TER to battery 29 through contact 33 of TR up, contact 30 of BPSR down, and contact 36 of BPR which has reclosed with the dropping out of BR. This starts the TER relay running and after a predetermined time interval, in this instance approximately one minute, relay TER closes its contact 39. The closing of contact 39 of this relay, then allows relay BPSR to pick up since one side of the latter relay is permanently con- .nected to one side of battery 29 and the other side of this relay is connected to the opposite sideofthe battery through contact 39 of TER and contact 36 of BPR. As relay BPSR picks up, it sticks up through its own front contact 30 and releases relay TER, reopening contact 39. It will be seen that whenever relay BR operates, dropping relay BPR, relay BPR cannot pick up to restart the timing cycle until check contact 38 of relay TER has closed. This then is the situation, whenever a train is stopped for more than a minute in any one of track sections 6T, 8T, 9T, .orv 11T, or if the train takes more than a minute to travel between adjacent resistors in any of the aforementioned track sections. In the latter case, as soon as another resistor is shunted, relay BR will again pick up momentarily and relay BPR drops out momentarily to deenergize relay BPSR to again energize the Warning signal systemby dropping out relay XR allowing its contacts 40 and 41 to close.

Relay TR remains in its energized condition corresponding to the position of its contacts 32, 33 and 34 as shown on the drawing until a train enters either track section 7T or T in which the crossing is located. Assuming therefore that thetrain has proceeded through section 8T, in a direction toward the crossing, shunting successively resistors 17, 16 and 15, and then enters section 7T, relay TR will immediately be shunted through the axles of the train. This opens the circuit to the XR relay by opening of contact 34 of the TR relay and the warning signals are again energized. The display will persist as long as the train is in section 7T because relay TR will remain positively shunted, holding open its contact 34 and thus removing power from relay XR and applying power to relay EOR. Track relay TR will not pick up until such time as the last car of the train clears track section 7T and enters track section 6T.

Referring again now to the condition of the system whenever a train is in, for example, section ST and proceeding toward the crossing, and consider the situation whicharises when the train enters section 7T and shunts the TR relay before the TER relay has completed its cycle. Dropping of the TR relay opens one contact 33 and closes another, which energizes the THR relay. The latter is a thermal time delay relay which will close its contact 50 after a predetermined time, in this instance about ten seconds. Closing of contact 50 by the THR re- .lay permits relay BPSR to pick up through contact 32 down of relay TR, contact 50 of THR and contact 36 of BPR. When BPSR is picked up under these conditions, it removes current from the THR relay, which serves to reopencontact 50 after a few seconds of cooling time. The thermal relay THR is utilized to pick up the BPSR :relay, rather than a back contact of relay TR, to prevent picking up of the BPSR relay due to a momentary shunt at the crossing of relay TR as might be caused, for example, by a metal tread caterpillar tractor or the like proceeding over the crossing and momentarily shunting track sections 7T or 10T.

An additional winding 26, which is permanently energized, tends to prevent the transformer core from becoming saturated, but it is not necessary for the operation of these circuits.

From theforegoing, it will be apparent that the hereinbefore described circuit provides for discontinuing the warning signal display after a certain time interval to allow for situations such as a train stopping at a station within the approach control section, and further that it provides for re-establishing crossing warning protection when such a train again moves toward the crossing, and that it further provides back-up protection for a train which has passed over the crossing and then stops and 'again-starts toward the crossing without clearing the normal approach control section.

From the foregoing, it will be apparent to those skilled in the art, that there is herein shown and disclosed a novel and useful gradecrossing protection system having numerousadvantages not available in prior art devices.

We claim:

1. In a control system for a highway crossing signal adjacent the intersection of a pair of railway tracks with a highway, in which each track is divided into crossing track sections and two approach control track sections, one on each side of the crossing section, the combination comprising: a series of insulated joints in each said approach control track section; resistance means connected to bypass each of said insulated joints and connected across the remote ends of each approach control section; means connecting all sections in series with each other, said means including a track relay, a source of electrical energy and a primary winding of a transformer; a biased polar relay connected to the secondary winding of said transformer; a signal means located at the crossing; means controlled by said biased polar relay for energizing said signal means in response to movements of a train toward said crossing in any one of said approach control sections in response to shunting of any of said resistors; timing means for automatically de-energizing said signal display after a predetermined time interval, said timing means also being controlled by said biased polar relay; and means including said track relay for continuously energizingsaid signal means whenever a train occupies the said crossing track section.

2. vIn combination: a pair of railroad tracks intersected by a highway; a signal at said intersection for warning highway tratfic of the approach of rail trafiic on either of the said tracks; means dividing each track into a series of insulated sections providing an unbroken rail crossing section and a pair of approach control sections, one on either side of the crossing section; each said approach section including a series of spaced insulated rail joints; a plurality of resistors, one connected to bypass each insulated joint in the approach sections and one connected across the rails at the remote end of each approach section; a track relay; a transformer including primary and secondary windings; a source of DC. voltage; means connecting one side of said track relay to the rail near the crossing end of one approach control section; means connecting the other side of said track relay to the corresponding rail in the crossing section; means for connecting all track sections and said track relay in series with the said source of DC. voltage, said means including the primary'winding of said transformer; a biased polar relay connected to the secondary winding of said transformer;

a second source of electrical energy; means controlled by operation of said biased polar relay in response to movements of rail trafiic toward the crossing section shunting any of said resistors in said approach control sections, for connecting said signal to said second source of electrical energy; timing means initiated by operation of said biased polar relay for disconnecting said signal from said energy source after a predetermined time interval, in order to deenergize said signal in the event that rail traflic stops for longer than said predetermined time interval in any of said approach control sections; and means including said track relay for continuously energizing said signal whenever the crossing track sections are occupied by rail traffic.

References Cited in the file of this patent UNITED STATES PATENTS 1,998,175 Thompson Apr. 16, 1935 2,071,995 Allen Feb. 23, 1937 2,085,930 Vanhorn July 6, 1937 2,106,680 Reichard July 25, 1938 2,186,794 Young Jan. 9, 1940 2,344,283 Bossart Mar. 14, 1944 2,628,306 McMahon Feb. 10, 1953 2,664,499 Muse Dec. 29, 1953 2,677,047 Mishelevich Apr. 27, 1954 2,684,435 Haines July 30, 1954 2,7 19,218 Miller Sept. 27, 1955 

